1. Field of the Invention
This invention relates to a method for decomposing a gaseous aliphatic halide compound and a decomposing apparatus employed therefor.
2. Related Background Art
With development of industrial technology in the recent years, a tremendous amount of aliphatic hydrocarbon halide compound (for example, ethylene chloride, methane chloride or the like) is used, its waste treatment becomes a serious problem. In addition, these used gases cause environmental problems such as contamination of natural environment, and numerous efforts are made for its solution. A specific treatment method is described as follows: For example, as a method for decomposing ethylene chloride using an oxidizing agent or a catalyst, there has been known an ozone decomposition method (Japanese Patent Application Laid-Open No. 3-38297) or an ultraviolet-ray irradiation method under the existence of hydrogen peroxide (Japanese Patent Application Laid-Open No. 63-218293) and the like. In addition, there is suggested use of sodium hypochlorite as an oxidizing agent (U.S. Pat. Nos. 5,525,008 and 5,611,642). In addition, there has been proposed a method for combining a sodium hypochlorite and ultraviolet-ray irradiation with each other (U.S. Pat. No. 5,582,741). Further, there has been known a method for suspending a photo catalyst and a liquid-like ethylene chloride consisting of semiconductor oxide particles such as titanium oxide under alkali conditions, and decomposing them by light emission (Japanese Patent Application Laid-Open No. 7-144137).
In addition to the foregoing, a photo-decomposition method for causing ultraviolet rays to be irradiated in a gas phase without using an oxidizing agent has already been attempted. For example, there has been proposed a method for ultraviolet-ray irradiation treatment of an exhaust gas containing an organic halogen compound to make an acidic decomposition gas, and then, rinsing the gas with an alkali to make it harmless (Japanese Patent Application Laid-Open No. 62-191025); an apparatus for applying air ventilation and air seasoning to exhaust liquid containing organic halide compound and ultraviolet-ray irradiation of a gas to be exhausted, and then, rinsing the gas with an alkali (Japanese Patent Application Laid-Open No. 62-191095) or the like. In addition, probably, as an example which is estimated as reductive decomposition, there has been known decomposition of ethylene chloride using iron powder (Japanese Patent Application Laid-Open No. 8-257570). Reductive decomposition has been reported for decomposition of PCE using silicon particles.